Mr. Pollack’s findings in collaboration with Scott Kemp, an expert on centrifuge technology at M.I.T., will be presented on Wednesday during a conference organized by the Asan Institute for Policy Studies in Seoul.

Mr. Pollack said he and Dr. Kemp had analyzed such open-source data as scientific journals, news reports and propaganda from North Korea to find evidence that the country is learning — or has already learned — how to make such crucial centrifuge components and related technologies and materials as uranium hexafluoride, vacuum pumps, frequency inverters, magnetic top bearings and maraging steel. He said that domestic production appeared to have begun no later than 2009.

North Korea shocked the United States in 2010 when its officials escorted a visiting American nuclear expert, Siegfried S. Hecker of Stanford University, to their main nuclear complex in Yongbyon, north of Pyongyang. There, they showed him a modern plant that they said housed 2,000 gas centrifuges, a technology that North Korea said it would use to enrich uranium for reactors but that American officials feared was a cover for making highly enriched uranium for atomic bomb fuel. Until then, the North’s sole source of weapons fuel had been plutonium gleaned from the waste of a mothballed nuclear reactor in Yongbyon.

Then, this April, at the height of tensions incited by the North’s nuclear test in February, the country declared that it would “adjust and alter the use of the existing nuclear facilities” for “bolstering up the nuclear armed force both in quality and quantity.” It said that included immediately restarting the Yongbyon facilities.

Last month, the Institute for Science and International Security in Washington cited satellite images to report that North Korea appears to have doubled the size of the building that housed the uranium enrichment plant in Yongbyon in recent months, and raising concerns that its enrichment capability would grow along with it.